The present disclosure relates to memory devices, and more particularly to semiconductor memory devices and methods of operating semiconductor memory devices.
Semiconductor chips are manufactured through semiconductor manufacturing processes, and then tested by a test device in a wafer, a die, or a package state. Defective portions of defective chips are identified through testing, and if some of memory cells are defective, repairs are performed to save semiconductor chips. Currently, semiconductor chips such as dynamic random access memories (DRAMs) have been continued to be reduced in size through fine processes, and accordingly, the possibility of errors occurring during manufacturing process have been increased. In addition, if defects are not detected through initial test processes, errors may occur during chip operations.